HYDRATION OF FLY ASH CEMENT CONTAINING HIGH ALITE CEMENT AND LIME STONE POWDER

Abstract

The authors have been reported that the strength of fly ash cement can be improved and obtained the same strength of ordinary Portland cement by using of high alite cement adjusting alite contents and free-CaO and addition of small amount of limestone powder. This paper discusses the hydration and hydrated products of this improved fly ash cement （AFC） compared with ordinary Portland cement （N） and generally fly ash cement （NF）. The reaction rate of fly ash （FA） or alite measured by XRD and selective dissolution method, and hydrated products was analyzed by SEM-EDS or solid state-NMR. The reaction rate of FA in hardened AFC is larger than that of FA in hardened NF. AFm is observed in hydrated N or NF. In hydrated AFC, AFt is also detected in addition of monocarbonate. The effect of LSP is observed at long term curing sample. Ca/Si ratio of calcium aluminous silicate hydrates （C-A-S-H） in hydrated samples are decreased and Al/Si ratio of C-A-S-H is increased by adding of FA. Bridge of AlO₄ and SiO₄ is increased by adding of FA, compared with the hydrated N. But this value of hydrated AFC is smaller than that of hydrated NF.